1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* 2 /*
3 * arch/alpha/lib/ev67-strcat.S 3 * arch/alpha/lib/ev67-strcat.S
4 * 21264 version contributed by Rick Gorton <ri 4 * 21264 version contributed by Rick Gorton <rick.gorton@alpha-processor.com>
5 * 5 *
6 * Append a null-terminated string from SRC to 6 * Append a null-terminated string from SRC to DST.
7 * 7 *
8 * Much of the information about 21264 schedul 8 * Much of the information about 21264 scheduling/coding comes from:
9 * Compiler Writer's Guide for the Alpha 9 * Compiler Writer's Guide for the Alpha 21264
10 * abbreviated as 'CWG' in other comments 10 * abbreviated as 'CWG' in other comments here
11 * ftp.digital.com/pub/Digital/info/semic 11 * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
12 * Scheduling notation: 12 * Scheduling notation:
13 * E - either cluster 13 * E - either cluster
14 * U - upper subcluster; U0 - subcl 14 * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
15 * L - lower subcluster; L0 - subcl 15 * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
16 * Try not to change the actual algorithm if p 16 * Try not to change the actual algorithm if possible for consistency.
17 * Commentary: It seems bogus to walk the inpu 17 * Commentary: It seems bogus to walk the input string twice - once
18 * to determine the length, and then again whi 18 * to determine the length, and then again while doing the copy.
19 * A significant (future) enhancement would be 19 * A significant (future) enhancement would be to only read the input
20 * string once. 20 * string once.
21 */ 21 */
22 22
23 #include <linux/export.h> 23 #include <linux/export.h>
24 .text 24 .text
25 25
26 .align 4 26 .align 4
27 .globl strcat 27 .globl strcat
28 .ent strcat 28 .ent strcat
29 strcat: 29 strcat:
30 .frame $30, 0, $26 30 .frame $30, 0, $26
31 .prologue 0 31 .prologue 0
32 32
33 mov $16, $0 # E : set up r 33 mov $16, $0 # E : set up return value
34 /* Find the end of the string. */ 34 /* Find the end of the string. */
35 ldq_u $1, 0($16) # L : load fir 35 ldq_u $1, 0($16) # L : load first quadword (a0 may be misaligned)
36 lda $2, -1 # E : 36 lda $2, -1 # E :
37 insqh $2, $16, $2 # U : 37 insqh $2, $16, $2 # U :
38 38
39 andnot $16, 7, $16 # E : 39 andnot $16, 7, $16 # E :
40 or $2, $1, $1 # E : 40 or $2, $1, $1 # E :
41 cmpbge $31, $1, $2 # E : bits set 41 cmpbge $31, $1, $2 # E : bits set iff byte == 0
42 bne $2, $found # U : 42 bne $2, $found # U :
43 43
44 $loop: ldq $1, 8($16) # L : 44 $loop: ldq $1, 8($16) # L :
45 addq $16, 8, $16 # E : 45 addq $16, 8, $16 # E :
46 cmpbge $31, $1, $2 # E : 46 cmpbge $31, $1, $2 # E :
47 beq $2, $loop # U : 47 beq $2, $loop # U :
48 48
49 $found: cttz $2, $3 # U0 : 49 $found: cttz $2, $3 # U0 :
50 addq $16, $3, $16 # E : 50 addq $16, $3, $16 # E :
51 /* Now do the append. */ 51 /* Now do the append. */
52 mov $26, $23 # E : 52 mov $26, $23 # E :
53 br __stxcpy # L0 : 53 br __stxcpy # L0 :
54 54
55 .end strcat 55 .end strcat
56 EXPORT_SYMBOL(strcat) 56 EXPORT_SYMBOL(strcat)
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